Witch Slapped, An Investigation

      Through my experience with stories and life I have come to the conclusion that there are two main reasons why a totally good and sane person, may turn their life around and become evil.  These reasons are greed, and inner desires, mixed with just one bad interaction.
       In Macbeth, Macbeth is started on a path to evil and destruction after one interaction.  Near the beginning of the play Macbeth is referred to by three witches as the thane(king) of two lands, and then the eventual king of Scotland. At the time he was only the thane of Glamis, so him discovering that he had become the thane of Cawdor greatly affected him.  This interaction isn't enough to turn a good man evil however.  This interaction reacted with one other aspect to push Macbeth onto a road to evil and destruction, Macbeth's greedy ambition.  Macbeth had always had the greed and ambition to do more with his life.  All it took for Macbeth to turn evil was the encouragement from the witches.
       In The Dark Knight (a work superior in every way to Macbeth),  the main antagonist, the Joker, understands this concept to the point.  The Joker, similarly to the witches, was able to take Harvey Dent (Macbeth), and lead with down a path to evil with just verbal reinforcement.  "You see, madness, as you know, is like gravity." says the Joker, "All it takes is a little push!".  The witches and the Joker are the little push that is able to knock a good man into insanity.
       Unfortunately, for Macbeth and Harvey Dent evil is a road that will always lead to an end.  If you are willing to do anything to achieve your goals, people will notice and fight back.  The path of evil always has one destination for these characters, (SPOILER ALERT) death.